INSTATIONARY HIGHLY TURBULENT HYDROGEN TUBE COMBUSTION PROCESSES IN OBSTACLE AREAS

The interaction between combustion and turbulence in hydrogen-air mixt ures in the early flame development phase is reviewed from the safety point of view. Detailed knowledge about the acceleration of hydrogen-a ir flames in real physical environments is needed to avoid deflagratio n-to-detonation transition (DDT). Depending on the initial and boundar y conditions, the burning velocity of the same hydrogen-air mixture ca n vary by an order of magnitude. A time-dependent two-dimensional flow algorithm, using a direct numerical simulation method (DNS) and inclu ding large-scale eddy simulation in complex channel areas, is presente d to calculate flame folding in the early burning phase after ignition . Complex mapping functions to realize different obstacle areas in tub es are presented. The effects of combustion on the structure of turbul ence in the how field, in front of the flame surface and effects of fl ow field instability on the flame development in tubes containing line or expanded obstacles are discussed.